In the pharmaceutical preparation field, the particle size of active pharmaceutical ingredients closely relates to the process and the quality of solid preparations. In a specific pharmaceutical preparation process, the suitable particle size of active pharmaceutical ingredients is usually selected according to the solubility and biofilm permeability of drugs. For example, a smaller particle size can be selected to promote the absorption of a drug with poor solubility and drug dissolution in the process of rate-limiting absorption. For another example, if the compressibility of a drug is poor, it can be improved by selecting an appropriate particle size and adding appropriate adjuvants. Therefore, the selective control of the particle size of active pharmaceutical ingredients is often involved in the process of the drug solid preparation. At present, the selective control of the particle size of active pharmaceutical ingredients is realized mostly by selecting different methods and process conditions of mechanical pulverization.
However, the process of mechanical pulverization has the problems of dust, environmental pollution, and great loss and so on. For some high active drugs, it exist high security risks that the operators may have adverse reactions in the process of mechanical pulverization. For example, a considerable number of hypnotics such as eszopiclone and alprazolam, have high activity, which can quickly take hypnotic effect with inhaling a low dose. When the operators pulverize such drugs, it is easy to cause operators the adverse reaction of rapid hypnosis, which will result in an accident. For another example, when pulverizing some high-activity hormones or anti-tumor drugs, the operators are easy to have serious adverse drug reactions if inhaling or touching the drug powder.
Also, so far by the widely used general method of mechanical pulverization (such as conventionally used universal pulverizer), the average particle size is generally about 100 micron. The dissolution characteristic of solid preparation produced by this method is still not ideal.
In the process of mechanical pulverization, to an active ingredient of a high-activity drug whose dosage is lower (such as ≦55 wt %) in the solid preparation, it also involves the problem of dispersal uniformity when mixing with adjuvants. Usually, the active pharmaceutical ingredients can disperse homogeneously in the solid preparation by carrying on the method of equivalent diluting and escalating the active pharmaceutical ingredients and adjuvants. But the operation of this method is complicated, and it also has the problems of dust, environmental pollution, great loss, security risks in labor protection and so on.
In addition, it should be also considered that whether the performances of the product can meet the needs when a solid preparation is produced. For example, whether a better content uniformity can be guaranteed should be considered. For another example, stability is the focus when the quality of a solid preparation is inspected, which includes whether the chemical stability of active pharmaceutical ingredients, the content of the related substance (i.e. impurities), the state stability of solid preparations and dissolution stability etc. are within the limit of drug standards during the storage period of solid preparations.
Therefore, in view of the above defects of the existing technology, it is urgent to seek a preparation method which can not only avoid the above defects in the process of mechanical pulverization but also ensure various performances of solid preparations well.